Control System for a Stent Delivery System

ABSTRACT

A control system for controlling movement of a medical device delivery system, a stent delivery system and a method for controlling movement of a medical device delivery system are provided. The control system includes a first extendable arm comprising a plurality of first struts interconnected at intermediate points and end points of the first struts. The first arm is movable between a first position and a second position and the first arm is operably connected to one of the first shaft and the second shaft. The control system also includes a first actuator operably connected to the first arm and the first actuator is operable to move the first arm from the first position to the second position. Movement of the first arm moves the first shaft relative to the second shaft to change the position of the second shaft relative to the first shaft.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/499,261, filed Jun. 21, 2011, which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

This invention relates to a medical device and, in particular to acontrol system for a device for delivering and deploying a stent and amethod of controlling the stent delivery system.

BACKGROUND

A self-expanding stent is typically introduced into the body using adelivery device that includes an outer sheath coaxially disposed andslidable over an inner catheter. The stent is disposed at the distal endof the device between the inner catheter and the outer sheath and heldin a compressed position by the outer sheath. The inner catheter and theouter sheath move coaxially with respect to each other. The stent may bedeployed by proximally pulling back the outer sheath relative to theinner catheter until the stent is exposed. The self-expanding stentexpands from the stent distal end to the stent proximal end as thesheath is proximally withdrawn.

Several problems may occur with the sheathed delivery device describedabove. The sheath release delivery devices are difficult to repositionor remove and slow to operate. The stent may only be partially deployedprior to reconstrainment of the stent by the sheath in order to stillreposition or remove the stent. Once the stent is fully deployed, i.e.radially expanded, the sheath cannot reconstrain the stent. For example,utilizing a conventional outer sheath/inner catheter delivery device maycause the physician to inadvertently use excessive force and pull backthe outer sheath too far, thereby prematurely deploying the stent in anincorrect position within a body lumen. At this step in the procedure,repositioning of the stent becomes difficult, if not impossible, becausethe stent has already radially self-expanded into the body lumen.

Additionally, in a typical sheath release device where the outer sheathis proximally withdrawn, the first portion of the self-expanding stentto make contact with the body vessel is the most distal portion of thestent. This type of release may cause difficulty in accurately placingthe proximal portion of the stent because the distal end of the stent ispositioned first while the proximal portion of the stent is stillcovered by the outer sheath. Accurate placement of the proximal portionof the stent and/or the stent body may be important in certainapplications, for example to prevent stent migration or to properly opena stricture along the entire length of the stricture. An additionaldrawback occurs with the sheathed stent delivery system where directvisualization of the stent is required. For example, in endoscopicallyplaced stents, the sheath tends to prevent or obscure the location ofthe stent, making accurate placement of the stent more difficult.

Further potential drawbacks for the conventional sheathed stent deliverysystem involve the stent placement within the system prior to use withina patient. Loading and anchoring of a conventional sheathed stentdelivery device is an involved process that may require preloading thestent into the device so that the stent remains compressed within thesheath during shipment and storage prior to use in the patient. Extendedcompression of the stent may lead to an alteration in the stentmechanical properties.

Conventional sheathed stent delivery devices also require a high forceto overcome the friction between the stent and the sheath that may alsobe a problem for proper stent placement within the patient. Theintroducer must be mechanically stronger to overcome the frictionalforces to avoid undesirable frictional consequences such as stretchingof the introducer catheters and hysteresis in the movement of the stent.The sheathed stent delivery device also requires more space within anendoscope compared to a sheathless device and also adds additionalexpense to the delivery system.

A longitudinally tensioned stent delivery system has been developed toavoid some of the drawbacks that can occur with a sheathed deliverydevice described above. The longitudinally tensioned stent deliverysystem includes an inner and an outer shaft coaxially positioned andlongitudinally moveable in relation to each other to expand andconstrain a stent positioned on the inner and outer shafts that canincrease the control, accuracy and ease of placement of a stent duringdeployment of the stent within a patient. A control mechanism forcontrolling the movement of the inner and outer shafts relative to eachother is needed to control the longitudinally tensioned stent deliverysystem to provide the ability to deliver the stent to the desiredposition and to be able to reconstrain, recapture, reposition and/orremove the stent after expansion of the stent.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide adevice and a method having features that resolve or improve on one ormore of the above-described drawbacks.

The foregoing object is obtained in one aspect of the present inventionby providing a control system for controlling movement of a medicaldevice delivery system having a first shaft and a second shaft, thefirst shaft is movable relative to the second shaft. The control systemincludes a first extendable arm comprising a plurality of first strutsinterconnected at intermediate points and end points of the firststruts. The first arm is movable between a first position and a secondposition and the first arm is operably connected to one of the firstshaft and the second shaft. The control system also includes a firstactuator operably connected to the first arm and the first actuator isoperable to move the first arm from the first position to the secondposition. Movement of the first arm moves the first shaft relative tothe second shaft to change the position of the second shaft relative tothe first shaft.

In another aspect of the present invention, a stent delivery system isprovided. The stent delivery system includes a first shaft and a secondshaft, the second shaft movable relative to the first shaft andcoaxially extending with the first shaft. The delivery system alsoincludes a stent operably connected to the first shaft and the secondshaft and a control system. The control system includes a firstextendable arm including a plurality of first struts interconnected atintermediate points and end points of the first struts wherein the firstarm is movable between a first position and a second position. The firstarm is operably connected to one of the first shaft and the secondshaft. The control system also includes a first actuator operablyconnected to the first arm wherein the first actuator is operable tomove the first arm from the first position to the second position.Movement of the first arm moves the first shaft relative to the secondshaft to change the position of the stent relative to the first shaft.

In another aspect of the present invention, a method for implanting astent using a medical device delivery system is provided. The methodincludes providing a control system. The control system includes a firstextendable arm including a plurality of first struts interconnected atintermediate points and end points of the first struts wherein the firstarm is movable between a first position and a second position. The firstarm is operably connected to one of the first shaft and the secondshaft. The control system also includes a first actuator operablyconnected to the first arm wherein the first actuator is operable tomove the first arm from the first position to the second position. Themethod further includes activating the first actuator, moving the firstarm in response to the activation of the first actuator, and changingthe position of the first shaft relative to the second shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a stent delivery system;

FIG. 2A is a sectional view of a distal portion of the delivery systemshown in FIG. 1 showing the stent in a constrained configuration;

FIG. 2B is a sectional view of a distal portion of the delivery systemshown in FIG. 1 showing the stent in an expanded configuration;

FIG. 3A is a side view of a control mechanism in a first positionaccording to an embodiment of the present invention;

FIG. 3B is a side view of the control mechanism shown in FIG. 3A in asecond position;

FIG. 4A is a side view of an embodiment of an actuator for a controlmechanism according to an embodiment of the present invention;

FIG. 4B is a side view of an embodiment of an actuator for a controlmechanism according to an embodiment of the present invention in asecond position;

FIG. 5 is a cross-sectional view of a first shaft and a second shaft anda portion of the control mechanism according to an embodiment of thepresent invention;

FIG. 6 is a side view of an alternative embodiment of a controlmechanism;

FIG. 7 is a side view of an alternative embodiment of a controlmechanism;

FIG. 8 is a side view of an actuator for an embodiment of the controlmechanism;

FIG. 9 is an enlarged perspective view of a portion of an arm of anembodiment of the control mechanism; and

FIG. 10 is an enlarged perspective view of a portion of an arm of anembodiment of the control mechanism.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention is described with reference to the drawings in which likeelements are referred to by like numerals. The relationship andfunctioning of the various elements of this invention are betterunderstood by the following detailed description. However, theembodiments of this invention are not limited to the embodimentsillustrated in the drawings. It should be understood that the drawingsare not to scale, and in certain instances details have been omittedwhich are not necessary for an understanding of the present invention,such as conventional fabrication and assembly.

As used in the specification, the terms proximal and distal should beunderstood as being in the terms of a physician delivering the stent toa patient. Hence the term “distal” means the portion of the deliverysystem that is farthest from the physician and the term “proximal” meansthe portion of the delivery system that is nearest to the physician.

FIG. 1 illustrates an exemplary stent delivery system 10 that may beprovided with a control system 100 according to an embodiment of thepresent invention. The delivery system 10 may be provided as anover-the-wire configuration or a rapid exchange configuration. The stentdelivery system 10 includes an inner shaft 22, an outer shaft 24 and ahandle 26 at a proximal portion 27 of the system 10. The handle 26 mayalso include a trigger 29 for actuating the control system 100. Thestent delivery system 10 also includes a stent 28 at a distal portion 30of the delivery system 10. One or more radiopaque markers 34 may beincluded on the delivery system 10 to indicate the position of the stent28. The stent delivery system 10 may also include a guide wire (notshown) extendable through a port 38 of the inner shaft 22 through adistal tip 41 at the distal portion 30 of the delivery system 10.

FIGS. 2A and 2B illustrate a distal portion 30 of an exemplary stentdelivery system 10 that may be driven by a control system in accordancewith embodiments of the present invention. The inner shaft 22 and theouter shaft 24 of the stent delivery system 10 are longitudinallymovable with respect to each other to facilitate the placement of thestent 28. The stent 28 may be connected to the inner shaft 22 by adistal constraining member 46 and to the outer shaft 24 by a proximalconstraining member 44. The stent 28 is movable between a constrainedconfiguration 40 shown in FIG. 2A and an expanded configuration 60 shownin FIG. 2B. As shown in FIG. 2A, the inner shaft 22 is moved distallyand the outer shaft 24 is moved proximally to position the stent 28 inthe constrained configuration 40. As shown in FIG. 2B, the inner shaft22 is moved proximally and the outer shaft 24 is moved distally toexpand the stent 28 from the constrained configuration 40 to theexpanded configuration 60. The embodiment of the distal portion 30 ofthe delivery system 10 is shown by way of example and meant to benon-limiting. Other configurations for the arrangement of the connectionof the stent to the inner and outer shafts for moving the stent betweenthe constrained and expanded configurations are also possible. In someembodiments, one of the inner shaft 22 and the outer shaft 24 may bemoved relative to the other of the inner shaft 22 and the outer shaft 24to move the stent between the constrained configuration 40 and theexpanded configuration 60.

An embodiment of a control system 100 is shown FIGS. 3A and 3B. Thecontrol system 100 may be provided to facilitate the manipulation of amedical device. The control system 100 may be provided as part of ahandle 26 at a proximal portion 27 of the stent delivery system 10 (SeeFIG. 1). As shown in FIGS. 3A and 3B, the control system 100 includes afirst extendable arm 102 operably connected to the inner shaft 22 and asecond extendable arm 104 operably connected to the outer shaft 24. Asshown in the end view in FIG. 5, the inner and outer shafts 22, 24 maybe positioned adjacent the extendable arms 102, 104 and extend coaxiallytherewith so that the first and second extendable arms 102, 104 mayexpand and collapse without interference with the longitudinal movementof the inner and outer shafts 22, 24 relative to each other. The firstand second extendable arms 102, 104 each include a plurality of crossedstruts 110 pivotally connected by a plurality of pins 112 so that thearms 102, 104 are expandable and collapsible to move the stent 28between the expanded configuration 60 and the constrained configuration40 as explained in more detail below. The struts 110 are connected at anintermediate point 121 and an end point 123. Depending on the positionof the strut 110 in the arm 102, 104, the struts 110 may be connected attwo end points 123. The first arm 102 includes a first end 106 and thesecond arm 104 includes a second end 108.

The first arm 102 and the second arm 104 are operably connected to acontrol member 114 having a first control pin 116 and a second controlpin 118 that are axially movable relative to each other. The first arm102 and the second arm 104 each include a first strut 110 a connected tothe first control pin 116 and a second strut 110 b connected to thesecond control pin 118. As shown in FIGS. 3A and 3B, the first andsecond struts 110 a, 110 b may be longer than the other struts 110. Thelonger first and second struts 110 a, 110 b, may be mechanicallyadvantageous in situations where a longer extension of the ends 106, 108of the arms 102, 104, respectively, away from each other is desired. Thelonger first and second struts 110 a, 110 b provide that a small changein the axial distance between a first attachment point 122 of the firststruts 110 a and a second attachment point 124 of the second struts 110b causes a larger increase in the distance between the first and secondends 106, 108 of the first and second arms 102, 104 as the attachmentpoints 122, 124 are moved closer together. In some embodiments, all thestruts 110 may be the same length, the struts 110 may be differentlengths, or the struts 110 on one arm may include longer struts or morestruts depending on the amount of longitudinal movement that is desiredfor the inner and the outer shafts 22, 24 relative to each other. Insome embodiments, the length of the first arm 102 is different than thelength of the second arm 104 such that the first and second arms traveldifferent distances.

As shown in FIGS. 3A and 3B, the control member 114 may be centrallypositioned between the first arm 102 and the second arm 104 so thatexpansion and contraction of the arms 102, 104 is equal and opposite.The first end 106 and the second end 108 are movable in equal andopposite directions to move the inner and outer shafts 22, 24 in equaland opposite directions so that the longitudinal tension on the stent 28is applied or removed with substantially equal force on both ends of thestent 28. As shown in FIGS. 2A and 2B, when equal and opposite force isapplied to and removed from the stent 28, a central portion 31 of thestent 28 remains in the same position as the stent 28 is moved betweenthe constrained configuration 40 and the expanded configuration 60.

FIGS. 4A and 4B illustrate an embodiment of an activator 128 for thecontrol system 100. The activator 128 includes the trigger 27 that isoperably connected to the control member 114 via first and second struts130 a and 130 b. The first strut 130 a is connected to the secondcontrol pin 118 at a connection 132 and the second strut 130 b isconnected to the first control pin 116 at a connection 134. The trigger27 is longitudinally movable to actuate the axial change in the firstand second control pins 116, 118 relative to each other. As the trigger27 is moved proximally as shown in FIG. 4B, the connections 132, 134 ofthe first and second struts 130 a, 130 b are moved apart and the firstand second control pins 116, 118 are moved in opposite directions. Theattachment points 122, 124 (shown in FIG. 3A) are moved closer togetherand the ends 106, 108 of the arms 102, 104 extend away from each otherto move the stent to the constrained configuration 40 shown in FIG. 2A.The trigger 27 may be returned to the starting position by any meansknown in the art. Non-limiting examples include spring return or manualreturn.

The control system 100 shown in FIG. 3B illustrates the system 100position when the stent 28 is in the expanded configuration 60 shown inFIG. 2B. The ends 106, 108 of the arms 102, 104 are positioned closertogether and the inner shaft 22 is moved proximally and the outer shaft24 is moved distally releasing the longitudinal tension on the stent 28.As shown in FIG. 3B, the attachment points 122, 124 are moved fartherapart so that the arms 102, 104 fold inward as the struts 110 pivot onthe pins 112. The corresponding position of the actuator 128 is shown inFIG. 4A where the connections 132, 134 are positioned closer togetherrelative to the position of the connections 132, 134 shown in FIG. 4B.

As shown in FIGS. 2A, 3A and 4A, the stent 28 is moved to theconstrained configuration 40 by pulling the trigger 27 of the actuator128 proximally. As will be understood by one skilled in the art, thecontrol system 100 may be provided so that pulling the trigger 27 of theactuator 128 proximally expands the stent 28, to the expandedconfiguration 60. By way of non-limiting example, the struts 110 a maybe connected to the second pin 118 and the struts 110 b may be connectedto the first pin 116 so that moving the trigger 27 proximally moves theattachment points 122, 124 away from each other and the stent 28 movesto the expanded configuration 60. The control system 100 may include alock to lock the stent 28 in the constrained configuration 40, forexample during delivery to the treatment site or in the expandedconfiguration 60.

Another embodiment of a control system 200 is shown in FIG. 6. Thecontrol system 200 may be provided as part of a handle 26 of the stentdelivery system 10. As shown in FIG. 6, the control system 200 may beprovided with a housing 250 and includes a first extendable arm 202operably connected to the outer shaft 24 and a second extendable arm 204operably connected to the inner shaft 22. The first and secondextendable arms 202, 204 each include a plurality of crossed struts 210pivotally connected by a plurality of pins 212 so that the arms 202, 204are expandable and collapsible to move the stent 28 between the expandedconfiguration 60 and the constrained configuration 40. The struts 210are connected at an intermediate point 221 and an end point 223.Depending on the position of the strut 210 in the arm 202, 204, thestruts 210 may be connected at two end points 223. The first arm 202includes a first end 206 and the second arm 204 includes a second end208.

The housing 250 may further include an actuator 252 having a firstactuator arm 254 and a second actuator arm 256 that cooperate tolongitudinally move the inner and outer shafts 22, 24 relative to eachother to expand and collapse the stent 28. The first and second actuatorarms 254, 256 move on pivots 258, 260. The first arm 202 and the secondarm 204 are operably connected to the actuator 252 so that the movementof the actuator 252 moves the arms 202, 204 that move the inner andouter shafts 22, 24. The housing 250 may further include a biasingmember 262 positioned between the first and second actuator arms 254,256 to return the first and second actuator arms 254, 256 to a startingposition.

The first arm 202 and the second arm 204 each include a first strut 210a connected to the first actuator arm 254 by a pin 212 a. The first arm202 and the second arm 204 also each include a second strut 210 bconnected to the second actuator arm 256 by a pin 212 b. As shown inFIG. 6, the first and second struts 210 a, 210 b may be longer than theother struts 210 of the first and second arms 202, 204 similar to thefirst and second struts 110 a, 110 b described above. In someembodiments, all the struts 210 may be the same length, the struts maybe different lengths, or the struts on one arm may include longer strutsor more struts depending on the amount of longitudinal movement that isdesired for the inner and the outer shafts 22, 24 relative to eachother.

The first arm 202 and the second arm 204 may be the same length ordifferent lengths depending on how far the inner and outer shafts 22, 24are to be longitudinally moved relative to each other. In someembodiments, the first and second extendable arms 202, 204 are equal inlength so that expansion and contraction of the arms 202, 204 is equaland opposite. The first end 206 and the second end 208 are movable inopposite directions to move the inner and outer shafts 22, 24 inopposite directions so that the longitudinal tension is applied to orremoved from the stent 28. For embodiments having arms 202, 204 withequal length, the longitudinal tension is applied with equal andopposite force. As shown in FIGS. 2A and 2B, when equal and oppositeforce is applied to and removed from the stent 28, a central portion 31of the stent 28 remains in the same position as the stent 28 is movedbetween the constrained configuration 40 and the expanded configuration60.

As shown in FIG. 6, when the actuator arms 254, 256 are pressed axiallyinward toward each other, the ends 206, 208 of the arms 202, 204 movelongitudinally away from each other and extend. The inner shaft 22 ismoved proximally and the outer shaft 24 is moved distally andlongitudinal tension is removed from the stent 28 to move the stent 28to the expanded configuration 60. In an alternative embodiment, theouter shaft 24 may be connected to the second extendable arm 204 and theinner shaft 22 connected to the first extendable arm 202 so that thestent 28 is moved to the constrained configuration 40. In thealternative embodiment, pressing on the actuator arms 254, 256 moves theends 206, 208 of the arms 202, 204 away from each other and extend thearms 202, 204. The outer shaft 24 is moved distally and the inner shaft22 is moved proximally and longitudinal tension is applied to the stent28 to move the stent 28 to the constrained configuration 40.

Another embodiment of a control system 300 is shown in FIG. 7. Thecontrol system 300 may be provided as part of a handle 26 at a proximalportion 27 of the stent delivery system 10 (See FIG. 1). As shown inFIG. 7, the control system 300 includes a first extendable arm 302operably connected to the inner shaft 22 and a second extendable arm 304operably connected to the outer shaft 24. In some embodiments, the outershaft 24 may be connected to the first extendable arm 302 and the innershaft 22 may be connected to the second extensible arm 304. The firstand second extendable arms 302, 304 each include a plurality of crossedstruts 310 pivotally connected by a plurality of pins 312 so that thearms 302, 304 are expandable and collapsible to move the stent 28between the expanded configuration 60 and the constrained configuration40 as explained above. The first arm 302 and the second arm 304 may beextendable to the same length or to different lengths. The first arm 302includes a first end 306 and the second arm 304 includes a second end308.

The first arm 302 is operably connected to a control member 354 having afirst control pin 356 and a second control pin 358 that are axiallymovable relative to each other. The first arm 302 includes a first strut310 a connected to the first control pin 356 and a second strut 310 bconnected to the second control pin 358. The second arm 304 is operablyconnected to a control member 364 having a first control pin 366 and asecond control pin 368 that are axially movable relative to each other.The second arm 304 includes a first strut 310 a connected to the firstcontrol pin 366 and a second strut 310 b connected to the second controlpin 368. As shown in FIG. 7, the first and second struts 310 a, 310 bmay be the same length as the other struts 310. In some embodiments, thestruts 310 may be different lengths, or the struts 310 on one arm mayinclude longer struts or more struts depending on the amount oflongitudinal movement that is desired for the inner and the outer shafts22, 24 relative to each other. Similar to the embodiments describedabove, the first and second struts 310 a and 310 b may be longer thanthe rest of the struts 310 to provide greater longitudinal extension ofthe arms 302, 304 with relatively small axial movement.

As shown in FIG. 7, the first and second arms 302, 304 may be controlledseparately by control members 354, 364 respectively so that one arm orboth arms may be extended and contracted to apply and removelongitudinal tension on the stent 28. As shown in FIG. 7, the first arm302 is contracted and the second arm 304 is expanded. The first end 306and the second end 308 are movable in opposite directions and the firstarm 302, the second arm 304 or both may be activated to move the innershaft 22, the outer shaft 24 or both the inner and outer shafts 22, 24relative to each other. In some embodiments, the control members 354,364 may be operated together so that expansion and contraction of thearms 302, 304 occurs at the same time. In some embodiments where thecontrol members 354, 364 are operated together, expansion andcontraction of the arms 302, 304 is in equal and opposite directions sothat the longitudinal tension on the stent 28 is substantially equal andopposite and the central portion 31 of the stent 28 remains in the sameposition as the stent 28 is moved between the constrained and expandedconfigurations 40, 60. (See FIGS. 2A and 2B.)

FIG. 8 illustrates an embodiment of an activator 340 for the controlsystem 300. The activator 340 may include a first trigger 27 a and asecond trigger 27 b. The first trigger 27 a is operably connected to thecontrol member 354 via first and second struts 330 a, 330 b and thesecond trigger 27 b is operably connected to the control member 364 viafirst and second struts 330 c, 330 d. The first strut 130 a is connectedto the first trigger 27 a and to the second control pin 358 at aconnection 332. The second strut 130 b is connected to the first trigger27 a and the first control pin 356 at a connection 334. The first strut330 c is connected to the second trigger 27 b and to the second controlpin 368 at a connection 336. The second strut 130 d is connected to thesecond trigger 27 b and the first control pin 366 at a connection 338.The triggers 27 a and 27 b are longitudinally movable to actuate theaxial change in the first and second control pins 356, 358 of thecontrol member 354 relative to each other and the first and secondcontrol pins 366, 368 of the control member 364 relative to each other.As the trigger 27 a is moved proximally, the control member 354 isactivated and the first arm 302 is extended. As the trigger 27 b ismoved proximally, the control member 364 is activated and the second arm304 is extended. As shown, the ends 306, 308 of the arms 302, 304 extendin opposite directions. The triggers 27 a and 27 b may be releasablylocked together with a connector 370 to cooperatively control activationof the control members 354, 364 to cooperatively extend and contract thefirst and second arms 302,304. The triggers 27 a and 27 b may bereturned to the starting position by any means known in the art.Non-limiting examples include spring return or manual return.

In some embodiments, the arms of the control mechanism may be providedin a double strut configuration for additional stability. For example,arms 102 and 104 may be provided with pairs of struts 110 as shown inFIG. 9. The pairs of struts 110 include a first set 111 and a second set113 that are substantially parallel to each other and extendabletogether. The struts 110 may be connected by pins 112 as described aboveand further include connectors 117 extending between the first set 111and the second set 113. Alternatively, the connectors 117 may beprovided to connect the first set 111 to the second set 113 and also toprovide pivot points for the struts 110 connected to each other. Thepairs of struts 110 may be included with any of the embodimentsdescribed above to provide additional stability.

In some embodiments, the struts 110 may be provided as molded componentsthat can be locked together by snap fit or tab and slot arrangements sothat fewer parts are needed to assembly the arms of the controlmechanism. Exemplary molded components 119 are shown in FIG. 10. Anyform of struts may be used to form the arms of the control member.Molded components are but one example of many types of struts that maybe used.

The above Figures and disclosure are intended to be illustrative and notexhaustive. This description will suggest many variations andalternatives to one of ordinary skill in the art. All such variationsand alternatives are intended to be encompassed within the scope of theattached claims. Those familiar with the art may recognize otherequivalents to the specific embodiments described herein whichequivalents are also intended to be encompassed by the attached claims.

1. A control system for controlling movement of a medical devicedelivery system having a first shaft and a second shaft, the first shaftmovable relative to the second shaft, the control system comprising: afirst extendable arm comprising a plurality of first strutsinterconnected at intermediate points and end points of the firststruts, the first arm movable between a first position and a secondposition; the first arm operably connected to one of the first shaft andthe second shaft; and a first actuator operably connected to the firstarm; the first actuator operable to move the first arm from the firstposition to the second position; wherein movement of the first arm movesthe first shaft relative to the second shaft to change the position ofthe second shaft relative to the first shaft.
 2. The control system ofclaim 1, wherein the control system further comprises a secondextendable arm comprising a plurality of second struts interconnected atintermediate points and end points of the second struts, the second armoperably connected to the other of the first shaft and the second shaft.3. The control system of claim 2, wherein the first arm is movable in afirst direction and the second arm is movable in an opposite directionto the first direction.
 4. The control system of claim 1, wherein themedical device comprises a stent having a first end portion operablyconnected to the first shaft and a second end portion operably connectedto the second shaft, wherein movement of the first shaft relative to thesecond shaft moves the stent from the constrained configuration to theexpanded configuration.
 5. The control system of claim 2, wherein thefirst extendable arm is movable independent of the second extendablearm.
 6. The control system of claim 1, wherein the plurality of firststruts comprises a first actuator strut connected to the first actuator,the first actuator strut having a length greater than the other firststruts.
 7. The control system of claim 2, wherein the second arm isoperably connected to the first actuator.
 8. The control system of claim2, further comprising a second actuator, the second arm operablyconnected to the second actuator.
 9. The control system of claim 2,wherein the first actuator comprises a pair of actuator arms.
 10. Thecontrol system of claim 9, wherein the first actuator further comprisesa biasing member for biasing the actuator arms.
 11. The control systemof claim 2, wherein the first arm and the second arm are extendable inequal and opposite directions.
 12. The control system of claim 1,wherein the first actuator comprises a first pin and a second pin, thefirst pin and the second pin being operably connected to the firstplurality of struts, the first pin and the second pin being movable toexpand and contract the first arm.
 13. The control system of claim 1,wherein the first plurality of struts are formed from molded components.14. A stent delivery system comprising: a first shaft; a second shaft,the second shaft movable relative to the first shaft and coaxiallyextending with the first shaft; a stent operably connected to the firstshaft and the second shaft; and a control system comprising: a firstextendable arm comprising a plurality of first struts interconnected atintermediate points and end points of the first struts, the first armmovable between a first position and a second position; the first armoperably connected to one of the first shaft and the second shaft; and afirst actuator operably connected to the first arm; the first actuatoroperable to move the first arm from the first position to the secondposition; wherein movement of the first arm moves the first shaftrelative to the second shaft to change the position of the stentrelative to the first shaft.
 15. The delivery system of claim 14,wherein the control system further comprises a second extendable armcomprising a plurality of second struts interconnected at intermediatepoints and end points of the second struts, the second arm operablyconnected to the other of the first shaft and the second shaft.
 16. Thedelivery system of claim 15, wherein the first arm is movable in a firstdirection and the second arm is movable in an opposite direction to thefirst direction to change the position of the stent.
 17. A method ofcontrolling the movement of a medical device delivery system, the methodcomprising: providing a control system, the control system comprising: afirst extendable arm comprising a plurality of first strutsinterconnected at intermediate points and end points of the firststruts, the first arm movable between a first position and a secondposition; the first arm operably connected to one of the first shaft andthe second shaft; and a first actuator operably connected to the firstarm; the first actuator operable to move the first arm from the firstposition to the second position; activating the first actuator; movingthe first arm in response to the activation of the first actuator; andchanging the position of the first shaft relative to the second shaft.18. The method of claim 17, further wherein moving the first arm changesa configuration of a stent to an expanded configuration or a constrainedconfiguration.
 19. The method of claim 17, further comprising moving asecond arm of the control system in a direction opposite to a directionof movement of the first arm.
 20. The method of claim 17, changing alongitudinal tension on a stent operably connected to the first shaftand the second shaft by changing the position of the first shaftrelative to the second shaft.